222 THE BILE. 



has been shown, by direct experiment, to facilitate the passage of oily 

 matters by osmosis through closed organic membranes or parchment 

 paper ; that is, oily matters will pass through these membranes more 

 readily when they are moistened with bile, than when simply wetted 

 with water ; and it is upon these experiments that the supposed func- 

 tion of the bile, in effecting the absorption of oil in the intestine, has 

 been based. But the villi of the intestine are not simply membranes 

 moistened with water. They are penetrated throughout by alkaline and 

 albuminous fluids, their bloodvessels contain an abundance of organic 

 material in the liquid form, and the fatty emulsion formed by the pan- 

 creatic juice is itself fully adapted for absorption by the villi. There 

 seems to be no good reason for assigning to the physical properties of 

 the bile, in this respect, any special importance for the absorption of 

 fatty substances. 



An action of quite the opposite nature has also been attributed to the 

 bile, namely that of precipitating the half-digested ingredients of the 

 food from their solution in the gastric juice. But there is reason to 

 believe that this also rests upon an error, and that there is no such 

 antagonism between the bile and the gastric juice in the intestine as 

 when they are mingled together in a test-tube. 



It has already been stated (page 159) that the bile precipitates by con- 

 tact with the gastric juice. If one or two drops of dog's bile be added 

 to as many cubic centimetres of fresh gastric juice from the same ani- 

 mal, a copious yellowish-white precipitate falls down, containing the 

 whole of the coloring matter of the bile which has been added ; and if 

 the mixture be then filtered, the filtered fluid passes through quite color- 

 less. The gastric juice, however, still retains its acid reaction. This 

 precipitation depends upon the presence of the biliary substances proper, 

 namely, the sodium glycocholate and taurocholate ; for if the bile be 

 evaporated to dryness and the biliary substances extracted by alcohol 

 and precipitated by ether in the usual manner, their watery solution will 

 precipitate with gastric juice, in the same way as fresh bile would do. 



Although the biliary matters, however, precipitate by contact with 

 fresh gastric juice, they do not do so with gastric juice which holds albu- 

 minose in solution. We have invariably found that if the gastric juice 

 be digested for several hours at the proper temperature with boiled 

 white of egg, the filtered fluid, which contains an abundance of albu- 

 minose, will no longer give the slightest precipitate on the addition of 

 bile or of a watery solution of the biliary substances, even in very large 

 amount. The gastric juice and the bile, therefore, are not finally incom- 

 patible with each other in the digestive process, notwithstanding the 

 reaction which takes place between them when artificially mingled. 



Although, however, the bile cannot be shown to exert any direct 

 action in the digestion of the food, similar to that of the other intestinal 

 fluids, yet there is evidence that it takes part, in the intestine, in some 

 process which is important, and even, in the long run, essential to life. 

 This is shown by the fact that if the bile be permanently diverted from 



